T H A N K YO U F O R AT T E N D I N G

KITCHEN VENTILATION SYSTEMS DESIGN

New Ideas & Technologies 2015

TOO OFTEN, THE KITCHEN IS...

As suggested by John A. Clark, P.E., Minneapolis

• Hot• Noisy• Smelly• Greasy• Slippery• Energy Consuming

MODERN SOLUTIONS

• Lowest Exhaust Rate at Peak Performance

• Robust Filtration• Dedicated Makeup Air• Demand Control Ventilation• Factory-Welded Ductwork• Water-Based Fire Suppression

RESULT: Integrated Design

INTEGRATED KVS DESIGN

• Avoids dynamic effects• Saves energy costs• Ensures peak

performance• Focus on safety,

comfort, efficiency

LOW EXHAUST RATES

LOW EXHAUST RATES

• Commercial kitchens are notorious for high energy use

• Poor design, inefficiency• Results in wasted $$$ to

restaurant owner

• Maximizing efficiency is crucial• ASTM1704 & UL710

ENERGY USE IN RESTAURANTS

RefrigerationSanitationFood PrepCoolingHeatingVentilationOtherLighting

Refrigeration

Sanitation

Food Prep

Heating

Cooling

Lighting

Ventilation

Other

SustainableFoodservice.com

HVAC 29%

HOW HOODS WORK

Effluent Rises

“Buoyant Thermal Plume”

• Newton (1687) described gravity, by which hot air rises

• Cooking effluents and products of combustion rise

• Effluent volume expands to fill space

ACHIEVING LOW EXHAUST RATES

• Adequate overhangs & vertical end panels reduce exhaust flow and ensure capture and containment

• Listed duct systems reduce static pressure

WHAT THE EYE SEES

Courtesy of FSTC CKV Lab

SCHLIEREN TECHNOLOGYAllows for Accurate Visualization of Air Temperature Gradients

SCHLIEREN TECHNOLOGY

Courtesy of FSTC CKV Lab

`

EFFLUENT CIRCULATION

Courtesy FSTC

Effluent circulates

in the hood

Coanda EffectFluid moving past a surface is drawn

to the surface

VISUALIZE LACK OF OVERHANG FOR FIRE CONDITIONS

RECOMMENDED OVERHANG

EQUIPMENTOVERHANG

FRONT SIDECharbroiler 18” - 24” 12”

Electric Fryer or Griddle 12” 6”Gas Fryer or Griddle 12” 12”

Conveyor Oven 12” 12” past conveyorConvection Oven 24” 6”

Open Burner Range 12” 12”Range with Shelves or

Salamander 24” 12”

Upright Broilers 18” - 24” 12”Solid Fuel 24” 24”

Woks 24” 24”Dishwasher 12” 24” inlet & discharge

Wall Canopy Hoods

END PANEL PERFORMANCE

Courtesy FSTC

VERTICAL END PANEL

EXHAUST RATES (LISTED VS. IMC)Type of Hood UNLISTED

IMC MINIMUM REQUIRED CFM per Linear Foot of HoodLight Duty Equip Medium Duty Equip Heavy Duty Equip Extra Heavy Duty

EquipUnlisted

Wall Canopy200 300 400 550

Unlisted Backshelf

250 300 400 Not allowed

Type of Hood LISTED

ETL / UL 710

TYPICAL LISTED CFM per Linear Foot of Hood

Light Duty Equip Medium Duty Equip Heavy Duty EquipExtra Heavy Duty

Equip

Listed Wall Canopy

150-200 200-300 200-400 350+

Listed Backshelf

100-200 200-300 300-400 Not recommended

LISTED

ASTM 1704Light Duty Equip Medium Duty Equip Heavy Duty Equip

Extra Heavy Duty Equip

Listed Wall Canopy

175 220 275 300

EQUIPMENT CLASSIFICATIONLight Duty Equipment

(400-450° F)

Medium Duty Equipment

(400-450° F)

Heavy Duty Equipment (600° F)

Extra Heavy Duty Equipment (700° F)

Ovens

Cheesemelters

Rethermalizers

Steam-Jacketed Kettles

Compartment Steamers

GriddlesFryers

Pasta CookersTilting SkilletsBraising PansRotisseries

Conveyor (Pizza) Ovens

Open-Burner Ranges

Electric/Gas Underfired Broilers

Salamander (Upright) Broilers

Chain Broilers

Wok Ranges

Appliances using Solid Fuel

(Wood, Charcoal, Briquettes and Mesquite) to

provide all or part of the heat source

Source: IMC

ROBUST FILTRATION

WHY FILTRATION? EFFLUENT

•Includes gaseous, liquid and solid contaminants•Products of combustion: Carbon monoxide, carbon dioxide and nitrogen oxide

•Harmful to human health, IAQ•Grease Characteristics:

• Both Vapor, Small and Large Particles

• Grease Vapor• Hotter cooking process =

more grease vapor

GREASE PROBLEMS

• Greasy Exhaust• Rooftop Damage• Environmental Impact• Grease Accumulation Behind Filters• Significant Buildup on Fusible Links• Fire Hazard with Grease Accumulation

in Duct and Plenum

GREASE PROBLEMS

GREASE EMISSIONS

ASHRAE RP-745

ASHRAE RP-1375

FILTER EFFICIENCY TEST

• ASTM F2519: • “Grease Particle Capture Efficiency of

Commercial Kitchen Filters and Extractors”• Pressure drop as function of airflow

through the filter• Particulate capture efficiency by particle

size• Incorporation of filter selection and effect on

design of entire system, including IAQ

FILTER EFFICIENCY TESTStandard Baffle

Cartridge Filter

HE-1

HE-2

2-Stage

ROBUST FILTRATION

• Improved baffle design increases grease capture at the source

• S-Baffle + Slotted Rear Baffle = Multi-Stage Filtration

• Issue of grease on the roof solved• Fewer duct cleanings required• Daily manual filter cleaning combined with

integrated self-cleaning of hood plenum results in very little grease, reduced fire risk

DEDICATED MAKEUP AIR

MAKEUP AIR PROBLEM?

System design incorporates makeup air tempering and delivery strategy

MAKEUP AIR• IMC 508.1.1 The temperature differential between

makeup air and the air in the conditioned space shall not exceed 10°F.• Exceptions:

1. Makeup air that is part of the air-conditioning system

2. Makeup air that does not decrease the comfort conditions of the occupied space

MAKEUP AIR: HOW & WHY

• Do No Harm: Deliver makeup air in an energy efficient manner without harming hood performance

• Makeup Air Options:• HVAC air via displacement diffusers, ceiling

diffusers, or perforated ceiling diffusers• Dedicated MUA: Exhaust hood with integrated

makeup air

HVAC AIR PROBLEMS

• Higher energy costs• Humidity gains with

continuous RTU cycling • May lead to high transfer air

velocities• Must separate HVAC & MUA

• Directional diffusers must be min.10’ from hood

• Perforated diffusers must be min. 5’ from hood

DEDICATED MAKEUP AIR APPROACH

DEDICATED MAKEUP AIR APPROACH

+

Makeup Air Delivery Moderate Heat/Cool

DEDICATED MAKEUP AIR

• Use DMUA unless all outside is satisfied by ventilation req’s without over-stressing RTUs

• Sensible Heating & Cooling: 55-85° F

• Supply plenum or dual plenum • 80% DMUA: Additional air

provided through HVAC RTU

DUAL PLENUM APPROACH

DUAL PLENUM APPROACH

DUAL PLENUM APPROACH

• Air velocity is critical • 140-160 FPM when plenum is placed 18” above

front edge of hood• 165-185 FPM when plenum is placed 24” above

front edge of hood• Air temperature

• 55-85° F• Supply risers

• Velocity 200-400 FPM• Multiple risers on longer hoods for better

distribution

VISUAL PERFORMANCE TESTSupply plenum approach aids in capture & containment performance

PACKAGED MUA UNIT•100% outside air applications

•Moderate tempering as needed

•Satisfies IMC 508.1

•Multiple Stage Cooling

•Up to 600 CFM/ton

PROPER TEMPERING HEATING

•Direct Fired Heater - 92% efficient

•Indirect Fired

•Electric

•Steam/Hot Water Coils

COOLING

•Direct Expansion (DX)

•Chilled Water Coils

DEMAND CONTROL VENTILATION

DEMAND CONTROL VENTILATION

• Automatically adjusts exhaust & makeup air fans according to cooking load

• Temperature sensor and variable frequency drives modulate fan speed

• Satisfies IMC 507.2.1.1, automatic activation requirement

• Rebates and incentives from many utility companies

FAN ENERGY SAVINGS & PENALTIES

Reduce Exhaust CFM

Savings in Fan Energy

0.1 0.27

0.2 0.47

0.3 0.66

0.4 0.78

0.5 0.87

Increase Exhaust CFM

Increase in Fan Energy

0.1 0.33

0.2 0.73

0.3 1.2

0.4 1.74

0.5 2.37

EXHAUST TEMPS VARY

74.893'

100.389

75.973

129.976

77.593

129.09

77.307

70

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Tem

per

atu

re (

F°)

Time

Golden'Corral'Raleigh,'NC'Sunday'4.24.11'

Grillhouse Pagoda

Pizza Hacienda

Large Buffet Chain Restaurant Raleigh, NC

FACTORY-WELDED DUCTWORK

GREASE DUCT ISSUES

• Liquid-tight welded ducts leak• Size and velocity• Static pressure drop• Integrity of welds and joints• Number of tees and elbows• Mitered elbows, non-radius• Access for cleaning• Clearance requirements

LEAKING DUCT: FIRE RISK

• IMC: Must be fully welded liquid-tight

• Heavy gauge black iron or stainless steel

• Duct leakage test: light bulb, smoke, pressure

DUCT CONSTRUCTION

IMC 506.3.2 • Joints, seams and penetrations: continuous liquid-

tight weld or braze made on external surface• Exceptions: Penetrations shall not be

required... where sealed by devices listed for application• Internal welding shall not be prohibited

provided that the joint is formed or ground smooth and provided with ready access

• Factory-built commercial kitchen grease ducts listed and labeled

CLEARANCE TO COMBUSTIBLESIMC 2009• 506.3.6 Grease duct…

serving a Type I hood shall have a clearance to combustible construction of not less than 18 inches (457 mm), and shall have a clearance to noncombustible construction and gypsum wallboard attached to noncombustible structures of not less than 3 inches (76 mm).

Hinged upblast exhaust fan

Roof

Ceiling

Exhaust Hood

10 ft

40inches

18 inches

Grease Duct

NFPA 96-2008 Appendix

Ductwork

CLEARANCE TO COMBUSTIBLES

• New UL 710 version allows for hoods to have a reduced clearance to combustible rating

• Intended for use adjacent to combustible construction of less than 18” clearance

• Temperatures on adjacent surfaces are measured and limited for rating

• 2 Tests: limited to max 117° F above ambient• 4 Tests: limited to max 175° F above ambient

• Labels include appliance duty classifications

Exhaust Hoods

FACTORY-BUILT GREASE DUCT

• Listed to UL1978 (Single)• Listed to UL2221 (Double)• 100% Dye Tested at Factory• Improved Fire Safety• No Field Welding• Zero & Reduced Clearance

to Combustible for Double Wall Duct

ROBUST DUCTWORK DESIGN

• Correct size and velocity• 1500-2000 FPM

• Static pressure drop estimated accurately

• Minimize number of tees and elbows, radius not mitered elbows

• Improved access for cleaning

WATER-BASED FIRE SUPPRESSION

RECENT FIRE

RESTAURANT FIRES

• 5,900 reported restaurant structure fires annually

• $172 million property loss • 75 civilian fire injuries • Cooking is the leading cause

of restaurant fires (41%)• Cooking materials (grease,

oil) were the most frequent items first ignited

US Fire Administration, April 2011

FIRE SUPPRESSION60 Years of Commercial Kitchen Fire Suppression ASHRAE Journal, June 2014• Proper application and maintenance of suppression

systems is an ongoing challenge• Fires in commercial kitchens most often start in or near

appliances• Fires are often related to inoperative appliance safety

devices

FIRE SUPPRESSIONSection 509 - Fire Protection System509.1 Where Required: Commercial cooking appliances

required by section 507.2.1 to have a Type I hood shall be provided with an approved automatic fire suppression system complying with the building code.

System Requirements:• Tested and Listed to UL300 Standard • Automatic activation • Means of manual operation • Appliance surface protection • Hood plenum and duct collar

SYSTEM TYPES

• Wet Chemical Systems• Discharge chemical agent• Appliance-specific protection and/or

overlapping protection• Water-Based Systems

• Discharge water and surfactant• Total flooding of hazard area

• Combination Systems• Discharge water and chemical agent

WATER-BASED FIRE SUPPRESSION

• Temperature detection with electronic activation

• Sprays appliances, hood plenum, exhaust duct

• Reliable: Continuous flow until fire is completely extinguished

• Meets UL300, IMC, and NFPA96

• Electronic monitoring and communication

UL300 TESTING FOR HOOD FIRE SUPPRESSION SYSTEM

SUMMARY

• Exhaust Flow Rates are critical: Find balance between low exhaust rate and peak performance

• Robust Filtration reduces greasy effluent, improves IAQ

• Dedicated MUA results in peak efficiency • Demand Control Ventilation allows for greatest fan

energy savings• Factory-Welded Ductwork results in best

performance, fewest leaks and fires• Water-Based Fire Suppression ensures highest

safety, significantly reduced fire risk

RESULT: INTEGRATED KITCHEN DESIGN

Streamlined KVS Design, from Hood to Fan

QUESTIONS?